Improvement in rotary steam-engines



AARON O. BALDWIN, OF BOSTON, MASSACHUSETTS.

IMPROVEMENT iN ROTARY` STEAM-ENGINES.

Specification forming part of' Letters Patent No. 58,206, dated September 25, 1866.

To all whom it may concern:

" Beit known that I, AAnoN CHARLES BALD- WIN, of the city of Boston, in the couuty of Suolk, in the State of Massachusetts, have l I consider the best manner of carrying my ininvented certain new and useful Improvements 1n Rotary Steam-Engines; and l do hereby declare tha-t the following' specification, under my hand and seal, fully describes and ascertains the nature of the said invention and in what manner the same is to be performed in and by the following statement:

My improvements consist in novel constructions, combinations, and dispositions of the parts by which an effective engine is produced, with the steam acting direct-ly to turn the shaft with a contin nous rotary mot-ion, and with the working parts mostly or entirely on the exterior of the cylinder, where they are easily accessible for adjustment, oili n g, or repairs.

The rst part of my invention relates to the arrangement on the main shaft of a central disk or wheel of reduced thickness toward the periphery, with two pistons attached, one on each face, and rotating in annular spaces in the cylinder, and so arranged that one shall pass its abutment at the time when the other is receiving` the full action of the steam.

The second part relates to firmly supporting the abutment which closes the annular working space of `the cylinder, and against which the steam acts to force the piston forward.

The third part relates to a form of piston to diminish the useless steam space in engines so constructed and arranged.

The fourth partrelates to the construction and arrangement of the valves and ports, so that one valve reciprocating at each revolution ofthe engine shall serve for the steam and the exhaust ports, and that the exhaust-port shall be open during the whole revolution, while the steam-port shall be open only at intervals, thereby sccurin g efficient and economical action and perfect facility of reversal with very simple and durable mechanism.

The fth part relates to a system of packing for preventing the leakage of steam inward from the annular steam-space in the cylinder.

The sixth part relates to means for adjusting such packing.

The seventh part relates to relieving the pist-ons from friction during that part of their revolution in which they exert no power.

I will first proceed to describe in detail what vention into practical effect, and will afterward point out what features I consider new. For the more perfect understandin thereof, I have prepared two sheets of illustrative drawings, forming part of this specification, and have marked the same with letters of refer ence corresponding with those in the following explanation:

Figure l is a side elevation of the entire engine. Fig. 2 is a plan view, partly in section. The section is on line X X in Fig, l. Fig. 3

is an end elevation, partly in section, with thev eccentrics and eccentric-rods omitted. The section is on line Y Y in Fig. 2. Fig. 4 is a longitudinal section on the line Z Z in Fig. 2, with the valve removed. or sketch showing a side view, on a smaller scale, of a simple arrangement of certain of the parts. Fig. 6 is a plan view of the same.

Similar letters of reference indicate like parts inall the gures.

Ais the main shaft of the engine. B isaiixed external cylinder, of which B B? are the heads, which are also fixed, and are the supports or bearings in which the shaftArotates. In the center, between these bearings, is a solid wheel or disk, a, firmly secured upon and rotating with the shaft A, and tapering slightly toward its circumference, where it its steamtight within the cylinder B by means of ordinary steam-packing upon the edge. (Not indicatedin the drawings.)

At a suitable distance within the external cylinder, B, and concentric to it, are two cylinders, B3, cast upon the inside of the heads B B2, respectively, and extending to the faces of the disk.l The annular spaces between the external and these inner cylinders constitute the actual working chamber of my engine.

Two pistons, a a?, itted accurately to the annular spaces above described, are rmly bolted on the opposite faces of the disk a at points so far out of line with each other that each piston passes its dead-point while the other is receiving the full force of the steam.

' The division of the annular space into two Fig. 5 is a diagram chambers by the disk remakes this eli'ectually a double engine, each side working independently of the other. When, in the description,

speak only of one side, the other is understood to be formed and to operate in thesame manner.

G are movable parts, which, operated by the rods c c2, slide in and out through corresponding rectangular apertures in the external cylinder, B, to close the annular chambers when required and serve as abutments for the action of the steam. As each piston arrives nearly in contact with its abutment C the latter begins to be withdrawn, and after the passage of the piston it immediately begins to be carried back to its place, throughout the movement just avoiding contact with the outline trace ofv the piston. A recess, x, prepared in the interior cylinder, B3, receives the end of the abutment C when fully homeand supportsit, as represented. So soon as this is done the steam is admitted, and the piston begins to contribute to the power of the engine by impelling the disk. The pressure of steam on the abutment, forcing` it iirmly against one side of groove x, diminishes the necessity of packing 'on the end. The sides'of the abutment, which are packed in the usual manner, are tapered or beveled slightly to correspond with the before-described bevel of the disk a and with a similar bevel of the heads B' B2. By this form of the parts the abutment is insured from striking the disk when entering, and friction is diminished by avoiding contact until the' abutment is nearly on its seat.

The easy removal and replacement of the abutment, as above described, allows a very rapid rotation of the engine without jarring or sudden wrenching of the parts 5 but the piston has time t-o pass the abutment some little distance before the latter comes fully toits place and is readyT to receive steam, thereby leaving a space to be illed with steam at each revolution before any effective work can be done; consequently I form my pistons in section much thicker at their inner than at their outer edges, andV fill up the useless space in this manner as much as isjpossible without producing an actual contact between the inner edge of the abutment and the inclined sides of the piston as the abutment is moved outward and inward.

The several rubbing-faces of the pistons may be rendered steam-tight by ordinary packin 0'. l prefer to groove the inner and thick faces ofthe pistons with parallel grooves, as shown in Fig. 4. These grooves retard and prevent the iiow of the steam past the piston in a manner analogous to that where corresponding grooves are employed in ordinary cylindrical pistons.

-I impel the abutments by a cam motion derived from the main shaft.

D D2 are eccentrics xed on the main shaft A, so that one is one-quarter of a revolution in advance of the other. E is a counter-shaft or supplementary shaft havingtwo crank-pins, e c2, placed quarterin g, like the eccentrics, and 0f exactly equal throw with them. d d2 are eccentric-rods,which communicate motion from the eccentrics to the crank-pins, so that the shaft E is caused to revolve in the same timel with the main shaft A. The shaft E carries two large face-cams, E E2, each having a working groove around its interior face, as indicated in dotted lines in Fig. 1 and in strong lines in Fi e'. 4. There is a separate rock-shaft, H, or an equivalent rocking sleeve upon it for each side of the engine, each moving independently of the other, and a wheel, h, on the lower arm of cach rock-shaft is receivedin the cam-groove above described. Thus, bythe rotation of the cams, a rocking motion is communicated to the shafts; and, by means ofthey upper arms, H H2, connected by the links l- P to the abutment-rods c c2, the required movements are transmitted to the abutment C.

I will now describe the means through which the steam is admitted to and discharged from the engine, so as to forbid the access of steam to each chamber while the abutments are being withdrawn and returned, and to allow of the reversing or workin g of the engine in either direction.

The exterior cylinder, B, is thickened or built out on the side in which the abutments are mounted, so as to provide for the several parts and passages required, or it may be formed in one or incre separate parts bolted steam-tight thereto.

Referring to Figs. 2, 3, and 4, which exhibit in section one side of the engine, the steam is admitted from the boiler through the passage J, horizontally, into the steam-chests K K2. From each of these steam-chests open the two ports or narrow passages m and a, communicating with the interior steam-chamber, and adapted to allow the steam to be either admitted or discharged at a proper distance above and below the abutmcnts C; also in each chest are the two ports P and Q, communicating freely with the exhaust-passage L.

A single slide-valve, B, is reciprocated up and down in each steam-chest by means of the valve-rod r, and controls the action ofthe steam. The form of the valve and its relation to the several parts are indicated in tolerably correct proportions in Fig. 3. The exact proportions of the lead and lap, 87e., in the adaptation of the slide-valve and ports to each other is a matter of very great importance, and no attempt is made in these drawings to indicate the precise conditions in these respects, but only to show the relations of the parts, so as to enable skillful engineers to properly construct the engine.

The valve R may be reciprocated at two stages, according to the direction in which the engine is turning, the highest point of the movement in its low stage being a little below the lowest point of the movement in its high stage.

There are two hollow throats in the valve, one of which may cover the ports m and l?, and the other the ports a and Q, and they are at such distance apart that when the valve is worked at its low stage, as represented, the upper throat will cover the exhaust-port P alone, while the lower throat will constantly cover and connect together the port a and exhaust-port Q, so as to cause them to constantly and freely communicate, and thus exhaust all the steam which presents itself to the port a. At each downward movement of the valve It, under these conditions, the port mis uncovered entirely during a portionof the revolution, and during that portion receives steam at full boiler-pressure from the steamchest, and leads it into the working chamber of the engine to impel the piston. At each upward movement of the valve It the port m is covered and closed entirely by the solid part of the valve. i

When the valve R is worked at its high stage, for moving the engine in the opposite direction, the upper throat constantly covers and connects m and P, which then exhaust freely, while the lower throat constantly covers the port Q. The valve R, at its upward movement, opens the port a for the admission of steam, and closes it at its downward movement.

The valves It, with their valve-stems r, rcceive motion from the loose rocking sleeves T T2, carried upon the fixed shaft T, and impelled by eceentrics F F2 on thema-in shaft and rods j" f2, as will be readily understood from the drawings. There are two arms on each sleeve for receiving this motion, and communicating` it, through the working arm t or t2 and the links U, to the upper ends of the valveestems r. The motion is received-through the upper or thelower arms by connecting the eccentricrods f f2 to the upper or the lower arms, ac cording as the engine is required to rotate in one direction or the other, by working the valve at its high or low stage.

I have represented a very simplerlockingspring and thumb-piece to enable the hook or recess on the eccentric-rod to be retained on the uppermost arm for transmitting the motion when required. The connection with the lowermost arm, when required, will be main-v tained by gravity. More elaborate mechanism 'may be employed, if, desired, for hooking and unhooking, so as to allow the reversing to be effected by the turning of a single lever; but I prefer for ordinary purposes the simple mechanism described.

Gare must be taken on'each side of the engine to adapt the slide-valve and the parts proper motions are communicated to the two slide-valves, and how the abutments which serve for the respective chambers are moved inward and supported in their recesses during a portion of each revolution, and are moved pressed closely between them, and also against i the inner cylinder, B3, making steam-tight joints at those points, while the inner edges of the ring V maintains a steam-tight contact with the disk a without following its revolution. Setscrews w are inserted through the cylinder-heads and bear against the ring W in order to adj ust the pressure of the packing. The ring W and setscrews w may be dispensed with, and the rubber inserted between the ring V and the solid casting, and will op crate very well if the rubber ring is of just `sufficient dimensions but if it leaks or presses too hard against the ring V it is not easy to remedy it, while the screws w and. ring W al low the adjusting of the pressure of the rings V and c with great perfection, and also allow of very delicate alteration to suit the expanA sion and contraction of the parts even while the engine is in motion.

In place of the indiarubbcr ring c any ordi nary steam-packing may be used between W and V, provided only that the material be slightly elastic and able to withstand the heat, oil, Src.

While the piston is traveling between the ports m and u it is ineffective, and therefore it is not necessary that it should there t the cylinder stcam-tight. Therefore, between the above points I recess the surfaces along which the piston travels-that is, the inner surface of the external cylinder, B, and the outer surfacc'of the inner cylinder, B3, also the inner faces of the heads Bl B2-so as to .leave but a very slight contact with the piston along that portion of its revolution, and thus diminish the friction of the engine.

I can dispense with the secondary shaft E, if desired, by Xing on the shaft A two cams corresponding in form to the cams E E2, and providing suitable connections therefrom to the lower arms of the rock-shaft or sleeves H.

Having now described my improvements and their operation, what I claim as my invention, and desire to secure by Letters Patent, is as follows: i

1. The central disk, a, diminished in thickness toward the periphery, with its pistons a a2 arranged thereon relatively to each other and to the correspondingly-tapercd abutments C, substantially in the manner and for the pur-I poses herein set forth.

2. The depression or groove- X in the part B3, for supporting the end of the abutment and preventing` the escape of steam past that point, substantially as and for the purposes herein set forth.

3. The within-described pistons, arranged as specified, the same being of a tapering or wedge form, with the base of the wedge presented inward and sliding on the fixed inner surface, B3, substantially as and for the purpose herein set forth.

4. The within-described combination and arrangement of the reciprocating valve R an d the four ports ou, a, P, and Q, whereby the exhaust-port is kept open during the whole revolution of the engine, while the steam-port is opened and closed as required-for the ntermittent admission ofthe steam at each revolution, and adapted to allow of reversing or working in the opposite direction, substantially as herein set forth.

5. The metal ring V and yielding ring` r,

in combination with the disk a and the inner cylinder, B3, for the purpose of preventing the escape of steam inward toward the shaft of the engine, substantially as herein set forth.

6. The adjusting-screws 10,0r their equiva' .ATHEn'roN T. BROWN,

G. FRANK BROWN. 

